Trunking communication systems are private wireless communication systems, which are developed in order to satisfy command and dispatch requirements of users and targets specific industry applications, and in which a large number of wireless users share a small quantity of wireless channels and which are multi-purpose, high performance wireless communication systems using command and dispatch as a main application. The trunking communication systems have wide application markets in fields such as government departments, public security, emergency communications, electric power, civil aviation, petrochemical industries and armies.
The trunking communication systems experience a similar development history to cellular mobile communication systems. The first generation trunking communication systems are simulation trunking communication systems supporting mainly voice communication. The simulation trunking communication systems entering China the earliest are Actionet systems from Nokia, which use MPT-1327 signaling to be applied in a 450 MHz frequency band. Hereafter, F.A.S.T from Japan and Smartnet from U.S. Motorola enter China and occupy more than 80% of the market share of our trunked market over a long period of time.
The second generation trunked systems are narrowband digital trunking communication systems rising in the 1990s and beginning to be deployed in China around 2004, and are trunking communication systems applied most widely at present in China. The digital trunking communication systems support voice and low speed data (at most 28.8 kbps) communications, and representative systems are terrestrial trunked radio (TETRA) systems defined by the European Telecommunications Standards Institute (ETSI), integrated digital enhanced networks (iDEN) systems of Motorola in USA, and two types of domestic trunked architectures, global open trunking architectures (GoTa) developed based on CDMAIX and GT800 systems developed based on GSM, respectively. From the domestic point of view, the growth of TETRA networks is the fastest in last two or three years. The number of the TETRA networks accounts for more than about ⅔ in the established digital trunking communication networks all over the country.
The trunked systems are different from public systems in that the trunked systems need to have efficient command and dispatch characteristics and require that the networks have high reliability and security.
Call control: a service bearer is established, maintained and released between a calling user and a called user according to a service request of the user.
Authentication and certification: authentication and certification are supported. Authentication functions include authentication of a terminal by a network side and two-way authentication of the terminal by the network side and of the network side by the terminal.
Fail soft: when a link between the network side and a base station or between network elements internal to the network side fails, the base station can provide limited trunked services for user terminals within its coverage range.
Network interconnection and intercommunication functions: the ability of intercommunicating with Public Switched Telephone Networks (PSTNs), public mobile communication systems (GSM/CDMA, TD-LTE, etc.), IP phones and other standard trunking communication systems. Trunking communication in 3GPP LTE is referred to as group communication service enabler (GCSE), the system architecture of which is shown in FIG. 1.
In order to utilize mobile network resources efficiently, the 3rd generation partnership project (3GPP) proposes a multimedia broadcast multicast service (MBMS), which is a technology for transferring data from one data source to a plurality of target mobile terminals to implement sharing of the network (including a core network and an access network) resources, thereby improving the utilization of the network resources (especially air interface resources). The MBMS defined by the 3GPP can not only implement low speed message class multicast and broadcast of plain texts, but also implement high speed broadcast and multicast of multimedia services to provide a variety of rich video, audio and multimedia services. This undoubtedly complies with trend of development of future mobile data and provides a better business prospect for development of the 3G.
The characteristics of the MBMS are large data volume of the services, long duration when a mobile terminal receives data and constant average data rate. The characteristics described above determine that both scheduling of the MBMS and control signaling configuration are semi-static, i.e., both scheduling information of the MBMS and control signaling information remain unchanged for a long time. Both information is sent periodically through a MBMS control channel (MCCH) and is collectively called MCCH information. A plurality of MCCHs may exist in an evolved MBMS (eMBMS) system, each MCCH corresponding to a different multicast/broadcast single frequency network (MBSFN) area, where only control information of the MBMS sent in the corresponding MBSFN area is born. FIG. 2 shows a schematic diagram of an MBMS structure in a LTE system.
At present, the industry is discussing the possibility of implementing trunking communication using the MBMS technology. In this application scenario, the following problem is found to exist in the related art during the research and practice of the related art.
The problem of how to ensure that UE can receive the required trunked service in time when the UE which is ready to receive the trunked service through an MBMS bearer moves inside and outside of the MBSFN area has not been solved yet.